Make a list of packing items to put in your checked luggage and in your carry on - This reduces the chances that you will forget something and have to bear unnecessary expenses to replace an item that you might need 

Confirm your flights ahead of time - Obviously very important, nothing worse than showing up to the airport only to realize that your flight schedule has changed and it's leaving 8 hours later. 

Book your first and last night's accommodation -  if you haven't booked a packaged holiday, guided vacation or a cruise. This is important because you don't want to show up to your destination only to realize you can't find a place to stay or have great difficulty doing so. At the end of your trip, try to stay at a  accommodation closer the airport,  particularly if you are leaving earlier in the morning. 

Scan or take a picture of your passport and email  to an email account that you can access anywhere in the world - Losing a passport in a foreign country can be one of the most stressful travel experiences one can have. The process of replacing one can be made much simpler when you have a copy of your passport.  If you have emailed a copy of it to an email address you can access anywhere, you never have to worry about losing a copy as it can always be accessed.

Plan your itinerary  - decide what are the key attractions/sights that you absolutely want to see, and which ones aren't as important. Try not to load up your days with too much activities, as time tends to move faster than what we expect and that can cause extra stress.   

Choose the right traveling companion - This is one of the most important ones. If you are traveling  by yourself, clearly this isn't an issue. However, if you are traveling with somebody,  they can either make things great or can ruin your trip. If you have any doubts about whether someone would be good to travel with, you may want to reconsider. Insurance - 

Make sure that you have proper cancellation and medical coverage. It's better to have it and not need, than need it and not have it. If you need to use your insurance while in destination , you should familiarize yourself with the process of making a claim, etc. Know what phone number you need to call, as well as what your insurance plan number is. 

Credit and Debit Cards - Carrying two credit cards is never a bad thing. There is always a chance that your credit card might be compromised while on a trip. If you have a back up credit card, that will solve many headaches.  Let your bank know that you are traveling to reduce the chance of your debit card/atm card being deactivated while away. 

Bring Local Currency - Whenever traveling out of country, always make sure you have some local currency with you before you arrive. Saves you time looking for an ATM machine or trying to find a place to exchange money. The most expensive place to exchange money is...you guessed it..the airport! 

Adaptors/Converters - Make sure you have the right adaptor/converter for the destination you are going to, especially if you are bring items like a laptop/tablet/smart phone, etc